1. Field of Invention
The invention relates to a workpiece formed with a pattern and a method and an apparatus for manufacturing the workpiece formed with a pattern, more particularly, to a technique of leaving free loops on a reverse side of a workpiece.
2. Description of Related Art
Conventionally, a sewing apparatus, such as a sewing machine, includes a needle that holds an upper thread and passes the upper thread through a work cloth, a thread take-up that tightens the upper thread, a device for driving the needle and the thread take-up, a thread loop taker that accommodates a lower thread bobbin, forms an upper thread loop in cooperation with the needle and the thread take-up and crosses the upper thread and the lower thread to each other, a feed dog that feeds the work cloth, and a device that drives the feed dog. A sewing operation is performed by which the work cloth is fed by driving the needle and the thread take-up vertically.
A general home embroidery machine includes an embroidery frame to which a work cloth is attached and a device for moving the embroidery frame in orthogonal directions (an X direction and a Y direction) in a horizontal plane, instead of the feed dog. The sewing operation is performed by which the embroidery frame is independently moved in the X direction and the Y direction, by a controller, based on embroidery data.
Recently, compact and lightweight sewing apparatuses and sewing equipment have been sold. It is expected that a sewing apparatus for children, having an embroidery function, will be in practical use in the near future. It is conceivable that such a sewing apparatus having the embroidery function will be a compact and lightweight sewing apparatus that has a relatively simple structure and sews an embroidery pattern using only an upper thread.
When a sewing operation is performed using an upper thread and a lower thread, the upper thread and the lower thread pull at each other in stitches formed on a work cloth. Therefore, free loops are not formed on a reverse side of the work cloth. Even when the sewing operation is performed using only the upper thread, no free loops are formed, because the thread is tightened by means of the thread in a stitch and the thread in a following stitch in continuous stitches pulling each other.
Conventionally, a pattern is formed on a work cloth in a state where a thread is under tension (no free loops), and then an adhesive, such as a double-sided adhesive tape, is adhered on a reverse side of the work cloth formed with a pattern. However, good adhesion of the work cloth can not be obtained when the work cloth is adhered to clothes.
When a sewing operation is performed using the upper thread and the lower thread as in a general sewing apparatus, the thread loop taker, the driving device for the thread loop taker, and the like are needed. Accordingly, the structure of the sewing apparatus becomes complicated. It is difficult to reduce size and weight of such a sewing apparatus. There has been proposed sewing equipment that performs a sewing operation using only the upper thread. However, stitches are liable to unravel because the upper thread does not cross the lower thread. Therefore, the stitches are far from perfect stitches and are not practical.
To date, there has been no proposed simple and practical technique of fixing free loops formed on a reverse side of a work cloth to the work cloth when the sewing operation is performed using only an upper thread. Further, there has been no idea put forth for a work cloth, having a special structure, that is sewn such that stitches and embroidery patterns do not unravel when the sewing operation is performed using only an upper thread.
The invention provides a workpiece formed with a pattern by which a plurality of free loops are fixed on a reverse side of the workpiece, and a method and an apparatus for manufacturing the workpiece formed with the pattern.
An apparatus that manufactures a patterned cloth such that an embroidery pattern is formed on its surface includes a sewing tool that passes a thread through a workpiece, a sewing tool driving device that reciprocates the sewing tool up and down, a moving device that relatively moves a workpiece holder having the workpiece and the sewing tool in a direction in a horizontal plane perpendicular to a reciprocating direction of the sewing tool, and a controller that controls the sewing tool driving device and the moving device to cause a thread to pass through the workpiece a number of times in different positions so that a plurality of free loops are left on a reverse side of the workpiece by frictional resistance between the workpiece and the thread passed therethrough, thereby forming an embroidery pattern on a surface of the workpiece. The apparatus for manufacturing the workpiece formed with a pattern is of the same structure as a sewing apparatus. However, the apparatus is not restricted to general sewing machines. The apparatus may be sewing apparatuses having various structures different from general sewing machines.
The workpiece holder, to which the workpiece is attached, and the sewing tool are moved relatively in orthogonal directions in the horizontal plane by controlling the driving device by means of the controller while the sewing tool is moved up and down by the sewing tool moving device. Accordingly, an embroidery pattern can be formed on the workpiece with free loops left on the reverse side of the workpiece.
When a thread forming a pattern is fixed using elasticity of the workpiece to which the pattern is applied, without using other thread or a thread in a previous or a following stitches, an embroidery pattern can be formed using only an upper thread. Further, an embroidery pattern can be formed using a workpiece including an elastic film member by which a plurality of free loops are left on a reverse side of the workpiece via resistance acting between the elastic film member and a thread while the thread is passed through the workpiece a number of times.
When the sewing tool is a hollow needle, a pattern and free loops can be beautifully formed. When a cut surface having an arc shape in cross section is formed in a workpiece, a thread can be surely fixed to the workpiece as a force to fix the thread to the workpiece is enhanced as compared with a cut surface having a circular shape, i.e., a round hole, in cross section. When a tip of the hollow needle is inclined with respect to its axis, a cut surface having an arc shape is formed in a workpiece as the hollow needle swings and passes through the workpiece.
When the cut surfaces having the arc shape in cross section are successively formed so that a tangent to a middle of the arc of the cut surfaces is not perpendicular to an arrangement direction of the cut surfaces, the possibility of cutting a thread by the hollow needle can be reduced to a minimum. When the fixing material is a sheet-type material having tackiness on both sides, a workpiece can be easily adhered to clothes and the like.
When the fixing material for fixing the free loops is applied on the reverse side of the workpiece, after processing on the workpiece is completed, the free loops do not come out. Accordingly, a pattern formed on a surface of the workpiece does not unravel. The fixing material may be adhesives applied to the workpiece in layers. Further, the fixing material may be a tape or a double-sided adhesive tape formed of adhesives.